1. Field of the Invention
The present invention relates to a vehicle room lamp to be mounted to an inner lining of a vehicle roof and, more specifically, to an insulating structure between bus bars for a vehicle room lamp which prevents bus bars disposed on a back surface of a case of the room lamp from being short-circuited due to carbon fibers contained in the inner lining when being mounted to a hole of the inner lining of the roof.
2. Description of the Related Art
A general structure of a vehicle room lamp is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2001-180372. This invention has a structure in which grooves are formed on a back surface of a case, bus bars are fitted in the grooves for connecting a female connector to be connected with a male connector extending from a power source with a light bulb and a switch, so that flashing of the light bulb is executed by turning the switch on and off.
In the vehicle room lamp in this structure, since fitting of the bus bars into the grooves can be performed automatically, there is an advantage in that manufacture in low cost is achieved. However, since the bus bars are exposed on the surface, there is a problem such that when it is fitted and fixed to the inner lining on the roof of the vehicle, carbon fibers contained in the inner lining, although they are short, fall between the bus bars disposed close to each other, and causes short circuit between the bus bars, which may result in blowout of a fuse.
Therefore, a case which can prevent the above-described short circuit between the bus bars was developed. This invention is disclosed in Japanese Unexamined Patent Application Publication No. 2003-327043, and configured by integrating respective bus bars which constitute a circuit via bridge portions, setting the entire bus bar into an injection molding machine for manufacturing the case by injection molding for molding the bus bar within the case, and then cutting and bending the bridge upward for establishing a circuit for controlling flashing of a light bulb.
In this invention, in order to prevent metal chips generated when mounting the case to the vehicle with a screw from entering into hole portions formed when cutting and bending upward the bridge portions to cause the short circuit, cap members for closing the holes are integrally formed when molding the case, and the cap members are fitted into the holes in the last step.
In the above-described vehicle room lamp with the bus bar molded therein, since a very difficult work to insert the bus bars at the time of injection molding is involved, there arises a problem of increase in manufacturing cost, and since it also requires a manual operation to fit the cap member formed integrally with the case into the respective holes so as to prevent the short circuit due to the metal chips, there arises a problem of increase in cost of the product as a whole.